Do you have questions about making the best decisions for fall herbicide applications? Amit Jhala might be able to help. Jhala, Extension weed management specialist with the University of Nebraska-Lincoln, recently fielded three common questions around the topic in a recent edition of the school’s CropWatch newsletter.1. Which formulation of 2,4-D should be used for fall herbicide applications?
“The ester formulation is relatively more effective biologically and likely to provide better weed control in the fall, but it’s also more volatile,” Jhala notes. “The amine [salt] formulation would be preferred for spring burndown application, particularly if sensitive crops are in the vicinity.”2. Which herbicides can be tank-mixed with 2,4-D for fall weed control?Common tank-mix partners include Clarity or Banvel (i.e. dicamba), Sharpen, Gramoxone and Valor, Jhala says. Adding a tank-mix partner will improve 2,4-D’s spectrum of control.What about glyphosate? Jhala says it’s OK if grass weeds are present, but skip it if they’re not.“It’s widely used during the crop season, and we already have six weeds in Nebraska resistant to glyphosate,” he says. “Applying glyphosate in the fall would only add more selection pressure.”3. Will fall herbicide application provide effective control of summer annual weeds?In a word – no. They don’t start emerging until May or even June, and too much time has passed from the time of the application.“If your field has a lot of pigweeds, applying an effective pre-emergence herbicide at crop planting will provide better control,” Jhala says.